With known virtualization technology, a plurality of virtual machines (virtual computers) is provided in a single physical computer, and mutually different operating systems (OS) can be executed on each virtual machine. Dedicated virtualization software is required to implement a virtual machine.
Such dedicated virtualization software includes software whereby a hardware resource having a storage apparatus such as a NAS (Network Attached Storage) is divided logically, forming a plurality of logical partitions (virtual storage apparatuses), and these logical partitions are operated independently (PTL 1). It should be noted that examples of technology relating to the virtual machine environment can be found in PTL 2 and 3.
With a file system, failover of the entire NAS is executed immediately even if for example only one part of the hardware (ports, memory or the like) in the NAS fails. In contrast, key business operations in banks, stock brokerage firms and the like employ block microcontrol, in which block access to a storage apparatus is performed using a SAN (Storage Area Network), and thus high reliability is achieved. A fallback operation is implemented in storage systems which execute block microcontrol, whereby if a failure occurs in part of the hardware the hardware in which the failure has occurred is disconnected from the system and operation continues. Thus shut-down of the entire storage system due to failure of one part thereof is prevented as far as possible in storage systems in which block microcontrol is executed.